Focusing mechanism for photographic or cinematographic objectives



Feb. 25, 1964 H. MAHN FOCUSING MECHANISM FOR PHOTOGRAPHIC 0RCINEMATOGRAPHIC OBJECTIVES Filed DSC. 2-2, 1961 IIIH INVENIUR: HerbertMAHN www AGENT United States Patent ice 3,122,079 FCUSING MECHANISR' FORPHTGRAPH lt CilQEh/ATGQRAPI'HC EXECTIVES Herbert Mahn, Bad Kreuznach,Germany, assigner to los. Schneider & Co. Gptische Werke, Bad Kreuznach,Germany, a company of 'Germany Filed Dec. 22, 196i, Ser. No. 161,659Claims priority, application Germany ian. 1d, 1961 5 Claims. (Ci.95--45) My present invention relates to a photographic or cmematographiccamera objective with one or more components (usually including a frontlens) that are axially displaceable for focusing purposes. n

Conventional focusing means include a rotatable but axially xed ringthreadedly engaging a nonrotatable axially shiftable lens barrel wherebythe latter can be advanced or retracted upon rotation of the ring. Thismode of adjustment is tedious in the case of objectives of large yfocallength, such as telephoto objectives, in which a considerable axialshift is needed for adjustment over the entire focusing range of thesystem. p

It is, therefore, an important object of my present invention to providemeans for enabling more rapid focusing in a telephoto objective orsimilar optical system.

It is a more particular objective of this invention to provide meansforenabling the focusing adjustment of an objective to be carried out bythe axial displacement of a control element.

Another specific object, allied with the `preceding one, is to providemeans for so connecting an axially displaceable lens support with anaxially shiftable control element therefor that the lens support movesat a slower rate than the control element whereby a more convenientscale spread and a more precise adjustment may be realized.

A further object of my invention is to provide means for combining thiscontrol element with a diaphragm preselector in such marmer that theuser can easily, and withione hand, open the diaphragm to its widestaperture while focusing the objective, with subsequent return of thediaphragm to its preselected stop position upon the release of thecontrol element Ifor ythe focusing means.

In accordance with my instant inventionfl provide in a photographicor'cinematographic camera objective, eg. one of the telephoto type, astationary holder anda lens support slidable in the direction of theoptical axis of the objective, in combination with axially displaceablecontrol means such as a slider and a lever connection between theholder, the lens support andthe control means whereby an `axial movementof the latter will result in a proportional, preferably reduceddisplacement of the lens support. The latter will usually be in theshapeof a barrel centered on the objective axis, the holderadvantageously comprising a tubular yinner housing and a generallycylindrical outer shell coaxially surrounding the lens barrel andprovided with peripheral slots to accommodate the articulatedconnections between the axially shiftable parts and the associated levermeans. The latter, in a preferred embodiment, consists of a ring or aring segment surrounding the inner housing with suflicient clearanceand/ or deformability to enable its swinging about a fulcrum providedfor it on the stationaryobjeetive portion, i.e. the housing or theshell. This fulcrum may be fixed or, pursuant to a further feature of'myinvention, may be axially shiftable to afford different ranges ofadjustment. It is to be understood that the term articulated as appliedto the connections and the ring or ring segment with the slider, thehousing and the lens barrel is to be construed broadly as encompassingnot only pivotal joints but any position engagement with freedom ofrelative angular displacement. n

3522,67@ Patented Feb. 25, 1964 l of a radially depressible stud orsimilar actuating element in the focusing slider to act upon the settingring of a conventional iris diaphragm through the intermediary ofanother curved member for disengaging a projection on this ring from aco-operating stop on an aperture selector whereby the diaphragm may beopened wide during focusing.

The above and other objects, features and advantages of my inventionwill become more fully apparent from the.

following detailed description, reference being made to theaccompanyingy drawing in which:

FIG. 1 is a side-elevational view (parts broken away) of a cameraobjective embodying the invention;

FIG. la is a cross-sectional view taken on the line `IA- IA of FIG. l;

i FIG. 2 is a viewsimilar to `BIG. l illustrating another embodiment ofthe invention;

FIG. 2a is a cross-sectional View on the line IIA-IIA of FIG. 2; and

FIG. 3 is a cross-sectional viewsimilar to `FIGS. la

and 2a but look-ing toward the rear of the objective, the

system showntherein representing a modification of that illustrated inFIGS. 1 and la.

The objective shown in FIGS. y1 and la: comprises a housing composed oftwo generally cylindrical portions, i.e. an outer shell 1 and an innertube 2, the shell 1 having a threaded rearward extension for attachingit to the body of a camera not shown. An iris diaphragm, not shown inthese figures but visiblefat 16 in FIG. 3, is adjustable in theconventional manner with the `aid of a rotatable but axially fixedsetting ring 1b. The tubular inner housing portion 2 extend-s coaxiallywithin shell 1 in relatively fixed position and, in turn, encloses alens barrel 3 which is axially slidable therein.y Lens barrel 3 supportsthe front assembly 4, 4a of a known type of telephoto objective and isprovided with a pair of outwardly projecting guide pins 6a, 6b whichpass through peripheral slots 2e, 2b in housing cylinder 2. The slotsZayand 2b, here shown to be straight and parallel to the optical axisalthough this need not be exactly the case, are disposed on oppositesides of a pair of lugs Ztl which rise from cylinder 2 and form afulcrumfor an annular'lever composed ol' a substantially semicircular bottomsegment 5 and a complementary top segment 5a, the latter being receivedbetween the lugs 2t) and swingable about the aligned pins 6a, 6b whiletelescopically yreceiving the ends of segment S to enable a change inthe circumference of the member 5, 5a as it swings about its pivotalaxis. It will be noted that segmenta is guided by lugs 2t) betweenhousing portions 1 and y2 with enough clearance to enable a full swingfrom the position shown in FIG. l` into an oPPOSitely inclined position,yet it will of course be possible to give the slots 2a, 2b a slightupward concavity if necessary. y'

' Shell 1 also has an axially extending peripheral slot 3 in which aslider 7 is manually displaceable; this slider hingedly grips the ringsegment 5 whereby the composite member 5, 5a acts as a lever totranslate any linear displacement ofthe slider into a similar butreduced displacement of the lens barrel 3. Slider 7 carries a pointery7a which co-operates with the pin 9 alongside slot 8, the scale beinggraduated `in units of distance which may range from, say, one meter (orabout three feet) atthc left-hand end thereof, as viewed in FIG. l, toinfinity at therright-hand end. It will thus be seen that a major v partof the length of the objective housing is available for the display ofthe scale markings whereas the extent ofthe actual displacement strokeof the lens barrel 3 is substantially less as evidenced by the 'reducedlength of the slot 2a in FIG. l.

The system of FIGS. 2 and 2a, in which elements similar to those o thepreceding embodiment have been designated by the same referencecharacters supplemented by a prime is designed to ai'iord an increaseddisplacement stroke for the lens barrel relative to the length of itshousing. ln this embodiment the lugs Ztl of FIGS. l and la have beenomitted and the fulcrum for the focusing lever is here provided by asecond slider l@ diametrically opposite slider 7. Slider lil is guidedin a peripheral slot ea' of shell l opposite the slot 8'; the lever hereconsists of a lower segment two short tubular segments 5a', 5brespectively bearing the pins 6a and 6b', and an upper segment 5cgripped by the slider ll). The nearly semiannular segments 5 and 5c aretelescopically received in the tubular segments 5a', 5b to facilitatethe necessary adjustment of the circumference of the loop delined bythese segments. Slider lil also carries a detent spring lill adapted tobe releasably indexed in several notches 12 of shell 1'; a second scaleda', swept by a pointer lila of slider lll, supplements the scale 9co-operating with the pointer '7a' of slider 7 The objective shown inFIGS. 2 and 2a can thus be readily focused in coarse steps by a shiftingof slider it? from one notch 12 to another, a tine or Vernier adjustmentbeing then possible by a suitable displacement of slider 7'.

ln FI". 3, wherein elements previously identified have been givenidentical reference characters followed by a double prime the focusinglever has been shown as a llexible semicircular ring segment 5 havingone end fulcrumed on housing portion 2 at 20 and having its other endpivotally hinged or otherwise articulated to slider 7". rThis slider isshown provided with a manually depressible stud 13 adapted to act upon acurved lever arm ld which is pivoted to slider 7 at 14a; a spring l5tends to swing the arms 14 outwardly about its pivot lita. The free endof arm 14 extends toward a location diametrically opposite the pivot pin6 of lever 5 and terminates in the vicinity of a projection leb rigidwith the setting 16a of iris diaphragm lr6. Projection leb extendsaxially within the annular space between shell fr and cylinder 2 for asulicient distance to remain aligned with the end of arm 1d in everyposition of slider 7". Shell Il" has an arcuate slot 22 within which adiaphragm preselector 17 is limitedly movable in circumferentialdirection so as to be frictionally or otherwise retained in any selectedposition of adjustment; a stop 17a on member l'l coacts with projectionb to arrest the setting ring 26a in the selected position into which itis urged by a spring 2l anchored to cylinder 2".

When the user depresses the stud i3, projection isb is disengaged fromstop 17a by the pressure of arm 14, against the forces of springs l5 and2l, and is rotated clockwise within the limits of a cutout 23 in housing2" to adjust the diaphragm i6 to wide-open position. Slider "i" may nowbe displaced longitudinally into a position in which the camera isaccurately focused upon an object as determined, for example, on afedex-type viewfinder or on a ground-glass plate substituted for the hlmholder of a camera. With the release o slider 7 and stud 13 thediaphragm assumes its preselected aperture and the objective is readyfor picture taking.

The system herein disclosed can be used, advantageously, with adepth-of-eld indicator of the type described and illustrated in mycopending application of even date entitled Depth-of-Field-lndicator forOptical Objective With Axially Shiftable Focusing Means, Ser. No. 161,658.

Various modifications of the details of construction shown in thedrawing are, of course, possible without departing from the spirit andscope of the invention as dened in the appended claims.

l claim:

l. A. camera objective comprising a stationary holder, a lens supportslidable on said holder in the direction t the objective axis, controlmeans movable on said holder in the direction of said axis, lever meanson said holder articulated at spaced-apart locations to said controliieans and to said support, and anchor means on said holder forming aiulcrum for said lever means whereby an axial displacement of saidcontrol means produces a proportional axial displacement of saidsupport; said control means comprising a first slider, said anchor meanscomprising a second slider displaceable parallel to said lirst slider ata substantially diamctrically opposite location and provided withindexing means for releasably retaining said second slider in a selectedaxial position.

2. A camera objective comprising a tubular housing provided with atleast one peripheral slot extending generally in the direction of thetube axis, a lens support axially slidable in said housing, controlmeans movable on said housing in the direction of said axis, arcuatelever means curved around said housing and provided with pivot meansextending through said slot into engagement with said support, saidlever means being articulated to said control means at a location remotefrom said pivot means, anchor means on said housing forming a fulcrumfor said lever means whereby an axial displacement of said control meansoutside said housing produces a proportional axial displacement of saidsupport inside said housing; an adjustable diaphragm in said housing,angularly displaceable stop means on said housing selectivelypresettable in dil-ferent positions of adjustment, setting means forsaid diaphragm provided with a projection extending outwardly towardsaid stop means for coaction therewith, spring means coupled with saidprojection for urging it into contact with said stop means, andactuating means on said control means provided with an extensiondisplaceable into temporary engagement with said projection fordeflecting it from contact with said stop means and adjusting saiddiaphragm to a wide-open position against the force of said springmeans.

3. An objective according to claim 2 wherein said lever means is ofsubstantially annular conhguration.

4. A camera objective comprising a generally cylindrical outer shellprovided with at least one peripheral rst slot parallel to the objectiveaxis, a tubular housing portion coaxially positioned within said shelland provided with at least one peripheral second slot generally parallelto said axis, a lens barrel coaxial with said housing portion andaxially slidable therein, a slider axially movable on said shell alongsaid lirst slot, arcuate lever means curved around said housing portionwithin said shell and provided with pivot means extending through saidsecond slot into engagement with said lens barrel, said lever meansbeing hinged to said slider at a location remote from said pivot means,and anchor means between said shell and said housing portion forming afulcrum for said lever means whereby an axial displacement of saidslider produces a proportional axial displacement of said lens barrel,said shell beinry provided with another peripheral slot parallel to andsubstantially diametrically opposite said rst slot, said anchor meanscomprising another slider displaceable on said shell along said otherslot and provided with indexing means for releasably retaining it in aselected axial position.

5. A camera objective comprising a generally cylindrical outer shellprovided with at least one peripheral tirst slot parallel to theobjective axis, a tubular housing portion coaxially positioned withinsaid shell and provided with at least one peripheral second slotgenerally parallel to said axis, a lens barrel coaxial with said housingportion and axially slidable therein, a slider axially movable on saidshell along said first slot, arcuate lever means curved around saidhousing portion within said shell and provided with pivot meansextending through said second slot into engagement with said lensbarrel, said lever means being hinged to said slider at a locationremote from said pivot means, anchor means between said shell and saidhousing portion forming a fulcrurn for said lever means whereby an axialdisplacement of said slider produces a proportional axial displacementof said lens barrel, an adjustable ating element extending 'irom saidbutton around part of said housing portion toward said projection fordeiecting it from Contact with said stop means and adjusting saiddiaphragm to a Wide-open position against the action of said axis andprovided with a projection extending outwardly 5 SOP means toward saidstop means for coaction therewith, spring means coupled with said ringand housing for urging said projection into Contact with said stopmeans, a button on said slider radially depressibie thereon, and acurved actu- References Cited in the file of this patent UNITED STATESPATENTS 2,259,415 Eddy Oct. 14, 1941

1. A CAMERA OBJECTIVE COMPRISING A STATIONARY HOLDER, A LENS SUPPORTSLIDABLE ON SAID HOLDER IN THE DIRECTION OF THE OBJECTIVE AXIS, CONTROLMEANS MOVABLE ON SAID HOLDER IN THE DIRECTION OF SAID AXIS, LEVER MEANSON SAID HOLDER ARTICULATED AT SPACED-APART LOCATIONS TO SAID CONTROLMEANS AND TO SAID SUPPORT, AND ANCHOR MEANS ON SAID HOLDER FORMING AFULCRUM FOR SAID LEVER MEANS WHEREBY AN AXIAL DISPLACEMENT OF SAIDCONTROL MEANS PRODUCES A PROPORTIONAL AXIAL DISPLACEMENT OF SAIDSUPPORT; SAID CONTROL MEANS COMPRISING A FIRST SLIDER, SAID ANCHOR MEANSCOMPRISING A SECOND SLIDER DISPLACEABLE PARALLEL TO SAID FIRST SLIDER ATA SUBSTANTIALLY DIAMETRICALLY OPPOSITE LOCATION AND PROVIDED WITHINDEXING MEANS FOR RELEASABLY RETAINING SAID SECOND SLIDER IN A SELECTEDAXIAL POSITION.